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Mixing at the B-Factories

Explore the study of neutral B oscillations and the measurement of dilepton mixing at the B-Factories, providing insights into flavor decomposition, effective Hamiltonian matrix, and possible CP violation. Discover the importance of same-flavor and opposite-flavor samples, time dependence, and high statistical analysis. Learn about other measurements of Δmd and the search for CP violation in mixing. Consider the unthinkable: CPT violation and the potential for new ideas in this field.

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Mixing at the B-Factories

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  1. Mixing at the B-Factories Daniel MarlowPrinceton University Beauty 2003 10/16/03 the “Iron City”

  2. Neutral B Oscillations Flavor decomposition: Time propagation: Effective Hamiltonian matrix:

  3. Standard Assumptions If CPT is a good symmetry: Eigenvalues: Expected to be small in the SM and often taken to be ~0

  4. . . . Neutral B Oscillations Eigenvectors: Indirect CP violation:

  5. Dilepton Mixing At the B-Factories the B0’s are produced in pairs such that The study of like- and opposite-sign dileptons provides a conceptually and experimentally simple way to observe the mixing, which is sensitive to Δm Same flavor: Opposite flavor:

  6. . . . Dilepton Mixing The relative populations of the same-flavor and opposite-flavor samples as well as the time dependence are important. The measurement is characterized by high statistics. In addition to Δmd, the measurement yields information on charged to neutral B production. Belle: 29.4 fb-1 PRD 67 052004

  7. Other Measurements of Δmd A variety of other techniques can be used to extract Δmd. “Tag” (exclusively reconstructed)

  8. Other Measurements of Δmd Unmixed Mixed BaBar: 23M B-pairs hep-ex/0212017 submitted to PRD

  9. Other Measurements of Δmd Belle & BaBar Combined

  10. Other Measurements of Δmd All experiments combined. Δmd is now very well measured!

  11. More Dileptons One can also search for CP violation in the mixing by looking for an asymmetry in the number of like-sign dileptons: In SM effects are expected to be small.

  12. CP & T Violation in Dileptons background signal Like-sign dilepton Δz distribution. 23M B-pairs

  13. CP & T Violation in Dileptons 23M B-pairs PRL 88 231801 (2002)

  14. Thinking the unthinkable: CPT Violation The mixing analysis can be extended to incorporate possible CPT violating effects via the inclusion of the parameter θ. If CPT is a good symmetry θ=π/2.

  15. Thinking the unthinkable: CPT Violation Belle did a second fit to their dilepton data, allowing for the possibility of CPT violation. Belle: 29.4 fb-1 N.Hastings et al.PRD 67 052004

  16. Coherent Time Evolution at the Y(4S) PEP-II (SLAC) B-Flavor Tagging BaBar W.Verkerke EPS2003 Exclusive B Meson Reconstruction Vertexing &Time DifferenceDetermination

  17. Time dependent B decay rates allowing DG0, CP/T/CPT violation BaBar has introduced a new parameterization wherein a fit is done to samples of the form Fit to where and BaBar W.Verkerke EPS2003 hep-ex/0303043

  18. Time dependent B decay rates allowing DG0, CP/T/CPT violation: fit results BaBar 82 fb-1 hep-ex/0303043

  19. The Future: Δmd We are nearing the end of the road, but a ~twofold improvement may still be in the cards. *Systematic error projections from C.Bozzi CKM Workshop CERN 2002

  20. The Future: CPT Parameters Once again, there is room for some improvement, but we are bumping up against systematic errors. We shouldn’t forget the possibility of new ideas!

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